Royal Enfield 1040045/B Piece Mudguard – Rear Mudguard Section for Thunderbird 350X (TBX) BS4

The Royal Enfield 1040045/B Piece Mudguard is a genuine OEM rear mudguard section designed specifically for the Thunderbird 350X (TBX) BS4 models. Listed in Royal Enfield internal scrap/parts documentation as “TB 350 X Rear Mudguard 1040045/B”, this part is part of the rear fender assembly that helps control mud, water and road debris thrown up by the rear tyre, keeping the bike cleaner and protecting the frame and underbody.

Unlike generic aftermarket fenders, this factory piece mudguard matches the original mounting points and contour of the Thunderbird X rear section, so it aligns correctly with the rear mudguard assembly, tail-lamp bracket and side panels. Royal Enfield price lists identify 1040045/B as “PIECE MUDGUARD,” confirming it as a dedicated OE component, not a universal accessory.

This is ideal if your TBX rear mudguard is cracked, rusted, or damaged in a minor crash and you want to restore the stock look and splash protection without compromising on fit or durability. Workshops and DIY owners can install it as a direct replacement using stock hardware (bolts, washers, stays). To minimise returns, we currently list only the confirmed Thunderbird 350X BS4 fitment; other claimed applications seen on third-party sites are noted separately as unverified.

Key Features

• Genuine Royal Enfield OE part – Part No. 1040045/B (“Piece Mudguard”) as per official RE price lists.

• Designed specifically for the Thunderbird 350X (TBX) rear mudguard section as listed in internal TBX part scrap documentation.

• Restores proper mud, water and debris control from the rear wheel for cleaner running and better protection of frame and underbody.

• Direct-fit OE geometry – correct curvature and mounting pattern to integrate with the TBX rear fender assembly and supporting brackets.

• Maintains factory look and alignment with tail-lamp, indicators and side panels when used with the correct TBX rear fender assembly.

• Manufactured to Royal Enfield quality standards for thickness, finish and durability – far superior to low-cost local fabrications.

• Supplied as a single mudguard piece (no stays, lamps, bolts or wiring included).

• Ideal for accident repair, corrosion replacement and professional workshop use on Thunderbird 350X BS4.

Compatibility Table

Confirmed Fitment (✔)
Based on internal scrap list + dealer catalogue cross-check:

CHECK PART NUMBER BEFORE PURCHASE 

Variants

• Single Variant:

  • Part Number: 1040045/B

  • Type: Rear piece mudguard (section of rear fender)

  • Finish / Color: Factory finish (as supplied by Royal Enfield for TBX rear fender)

No LH/RH or color variants are defined under this part number; those are handled by separate mudguard assembly part numbers.

FAQs

Q1. Will 1040045/B fit my Thunderbird 350X BS4?
Yes. Internal Royal Enfield scrap documentation clearly lists “TB 350 X Rear Mudguard 1040045/B”, and dealer listings show this as a TBX rear piece mudguard. This is the only application we treat as confirmed.

Q2. Does this also fit Thunderbird X 500 or standard Thunderbird 350/500?
Some online sellers claim compatibility with Thunderbird X 500 and Thunderbird 350/500 BS4, but we have not been able to cross-verify through an official RE microfiche for those models. 

Q3. Is this a full rear mudguard assembly?
No. 1040045/B is a “piece mudguard” – a specific section within the rear mudguard system. Complete painted rear mudguard assemblies (with different part numbers) are sold separately.

Q4. What hardware do I need for installation?
You generally reuse the OE bolts, nuts, washers and stays. If the bike has seen corrosion or accident damage, we recommend replacing rusty fasteners and rubber washers to avoid rattles and paint damage.

Q5. Is this genuine Royal Enfield or aftermarket?
This is a genuine Royal Enfield spare, listed as “PIECE MUDGUARD 1040045/B” in official price lists and sold in OE-branded packaging.